Crystal structure of 2,5-bis(diphenylphosphanyl)furan

In the title compound, C28H22OP2, each of the P atoms has an almost perfect pyramidal geometry, with C—P—C angles varying from 100.63 (10) to 102.65 (9)°. In the crystal, neighbouring molecules are linked via weak C—H⋯π interactions, forming supramolecular chains along the b-axis direction.


Related literature
For the uses of rigid diphosphine compounds in the preparation of homo-or hetero-bimetallic complexes, which have high potential for specific applications in catalytic processes, see: Kaeser et al. (2013); Xu et al. (2014). For the structural characteristics of these ligands providing control over the distance separating the two metallic centers and consequently, over the properties of the corresponding complexes, see: Brown & Lucy (1986). For the synthesis of bis(diphenylphosphanyl)furan, see: Brown & Canning (1983). For the resulting bimetallic complexes with Rh and Ir, see: Brown et al. (1984). For C-HÁ Á Á interactions, see: Munshi & Guru Row (2005 Table 1 Hydrogen-bond geometry (Å , ).
Cg is the centroid of ring C17-C22.

S1. Commentary
Rigid diphosphine compounds are important ligands for inorganic chemists as they can be used in the preparation of homo-or hetero-bimetallic complexes, which have high potential for specific applications in catalytic processes (Kaeser et al., 2013;Xu et al., 2014). The structural characteristics of these ligands provide control, among other things, over the distance separating the two metallic centers and consequently, over the properties of the corresponding complexes (Brown et al., 1986). Thus, as part of an investigation in the field, some thirty years ago (Brown et al., 1983) bis(diphenylphosphanyl)furan was synthesized for selective binuclear chelation and the resulting bimetallic complexes with Rh and Ir were isolated and latter tested in alkene hydrogenation (Brown et al., 1984), showing a poorer activity than the corresponding mononuclear analogues. However, we believe that this diphosphine ligand is still of great interest for an exhaustive coordination study. In former reports the ligand was not spectroscopically characterized, nor its crystal structure determined, so here we report its full characterization and solid-state structure studied by single-crystal X-ray diffraction.
The molecular structure of the title compound, Fig. 1 In the crystal, the packing is stabilized via weak C-H···π interactions (Munshi & Guru Row, 2005), involving adjacent molecules, forming a supramolecular chain along the b axis direction (Table 1 and Fig. 2).

S2. Synthesis and crystallization
Although the title compound could be prepared in high yields by reaction between dilithiofuran and 2 equivalents of chlorodiphenylphosphine (Brown & Canning, 1983), here it was obtained in 23% yield as a side product from the synthesis of 2-(diphenylphosphanyl)furan: nBuLi in hexane solution (8.25 mmol) was slowly added to a furane solution

S3. Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms were positioned geometrically and constrained using the riding-model approximation: C-H phenyl = 0.95 Å with U iso (H phenyl )= 1.2 U eq (C), and C-H furanyl = 0.95 Å, with U iso (H furanyl ) = 1.2 U eq (C).

Figure 1
The molecular structure of the title compound, with atom labeling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
View of the C-H··· π interactions (dashed lines; see Table 1) linking adjacent molecules. Hydrogen atoms not involved in these interactions have been omitted for clarity.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.